Depending on the circumstances, falling asleep first after sex can be a gamble. You don't want to seem rude and refuse to snuggle, but also you are tired. And if you're not yet on a let-it-all-hang-out basis, you might be paranoid that if you fall asleep and start drooling, your efforts to seem suave and mysterious will be dashed. Or, if you've just slept with your live-in partner and there is only one slice of that delicious pie left in the fridge, falling asleep first can mean that sneaky bastard will go down there while you're blissfully passed out and eat the last of it. See? It is a complex game with serious consequences.

That must be why some evolutionary psychologists at University of Michigan and Pennsylavnia's Albright College decided to study after-sex sleeping behaviors and what they mean. Interestingly, they found a relationship between how quickly a person falls asleep after sex and how much desire their partner has to bond with them. They surveyed 456 people about their experiences and desires after sex, including who fell asleep first after sex and who fell asleep first when the couple went to bed but did not have sex. Lead author of the study, Daniel Kruger, explains the findings, "The more one's partner was likely to fall asleep after sex, the stronger the desire for bonding."

So basically people whose sexual partners drifted off first were left sitting awake wanting to cuddle and chit-chat. It works as a sort of the "leave them wanting more" method of post-coital gamesmanship. Though researchers explained that it could also be that people fell asleep as a subconscious way of avoiding talking about commitment. Yikes! That seems awfully crafty—isn't it just as likely that the person simply had a long day at work and was not trying to engage in some kind of evolutionary mind fuck? I guess that's for you to determine on a case-by-case basis.

One good piece of news in terms of tired stereotypes: The study looked at whether men or women were more likely to fall asleep after sex, and, in a dramatic reversal of every "man passes out immediately after disengaging from woman" scene in romantic comedies, researchers actually found that it was not any more common for men to fall asleep first than women. Hurray for equality! And actually women were more likely to fall asleep first when no sex was being had. One kind of sad sounding reason for that? Men might be staying awake in an attempt to get their partner to have sex…but are only rewarded with delicate snores from the other side of the bed. Alas, somebody has to be the one to close their eyes first.